An experiment was conducted at Kom El-Qanater, Abo-Houmse, El-Bihera, Egypt season of 2016-2017, to study the effect of some recommended insecticides to control cotton bollworms mixed by a fungicide to control the cotton boll rot disease, and the effect of this mixing on the efficiency of bollworm insecticides. The experiment was carried out under field conditions in randomized complete block design with three replications in four treatments and compared with untreated cheek. Cotton variety Giza 86 was used in the experiment. Meanwhile, three Successively sprayed were used two insecticides Super Alpha^®10% EC (alph-cypermethrin) and Dora^® 48% EC (chlorpyrifos) were recommended against the cotton bollworms, where they were used individually in the 1^st and 2^nd treatments and mixed with Tecto^® 50% SC (thiabendazole) fungicides in the 3^rd  and 4^th treatments. The obtained results showed that the field application of two recommended insecticides against the cotton bollworms gave a high significant efficacy when dividedly mixed with thiabendazole as fungicide  (Tecto^® 50% SC). The average values of bollworms/100 bolls were significantly decreased 1.22 and 1.88  for alph-cypermethrin + thiabendazole mixture, 1.33 and1.66 for chlorpyrifos  + thiabendazole mixture during the two seasons of evaluation respectively, comparing with the values in the treatments free fungicide or the check treatment. Moreover, each evaluated mixture indicated that the infested of the boll rot was significantly decreased as 1.33 and 1.44 with 1^st and 2^nd mixture in both season respectively. The cotton yield was increased as % values to be 100 and 90 with alph-cypermethrin, 83.3 and 76 with  chlorpyrifos, 150 and 137 with alph-cypermethrin + thiabendazole mixture and 150 and 136 with chlorpyrifos + thiabendazole mixture in both seasons respectively. The obtained finding may be concluded that the thiabendazole as fungicide when mixed with the evaluated insecticides can improve effectiveness against the cotton bollworms and decrease the boll rot disease. In addition, these treatments can increase the cotton yield to a high significant value.